High power electric discharge lamp with cooled base assembly

ABSTRACT

Fluid cooled high power discharge lamp, more particularly a high pressure xenon discharge lamp with a power input of more than 10 kW capable of being disassembled. A cooling system is included in the base assembly. A clamping ring clamps a coupling flange in which a plurality of ducts and tubes for coolant are embedded; the coolant cools both the electrode and the lamp base assembly. Resilient packings are interposed between the component parts, in the vicinity of the ducts, to be cooled by the coolant.

O United States Patent 1 1111 3,816,784

Weninger June 11, 1974 HIGH POWER ELECTRIC DISCHARGE [56] ReferencesCited LAMP WITH COOLED BASE ASSEMBLY UNITED STATES PATENTS [75]Inventor: Gerhard Weninger, Munchen, 3,366,814 1/1968 Sileo 313/32Germany [73] Assignee: Patent-Freuhand-Gesellschaft fur Primary Karlsaalbach elektfische Gluhlampen mbH Asszstant Examiner-Darwin R.Hostetter Munchen Germany Attorney, Agent, or FirmFlynn & Frlshauf [22]Filed: May 3, 1973 57 ABSTRACT PP No.1 ,9 2 Fluid cooled high powerdischarge lamp, more particularly a high pressure xenon discharge lampwith a power input of more than 10 kW capable of being dis- [30] ForelgnApphcatlon Pnomy Data assembled. A cooling system is included in thebase May 8, 1972 Germany 2222454 assembly. A pi g g Clamps a p g flangein which a plurality of ducts and tubes for coolant are [52] US. Cl313/32, 313/22, 3311343492, embedded; the coolant cools both theelectrode and 51 l Cl 61452 the lamp base assembly. Resilient packingsare inter- 'P i 3 39 posed between the component parts, in the vicinityof I 0 I 3 the ducts, to be cooled by the coolant.

14 Claims, 4 Drawing Figures PATENTEDJUNI 1 I974 3316784 SHEET 1 0F 4PATENTEDJUN 11 m4 3Q816L784 snm z or 4 HIGH POWER ELECTRIC DISCHARGELAMP WITH COOLED BASE ASSEMBLY The invention relates to a high powerelectric discharge lamp with separable, liquid-cooled base assembly andwith a liquid-cooled electrode such as, e.g., high pressure xenondischarge lamps with a power input of more than kW.

It is known to cool the electrodes and the base assemblies of high powerelectric discharge lamps by means of a liquid. Some lamps of this typecan also be disassembled.

The high pressure xenon discharge lamp disclosed in U.S. Pat. No.3,256,383 can be disassembled. No special cooling in the region of thehighly stressed joints is provided so that lead joints have been used.It is common practice to use such lead joints when the base assembliesare insufficiently cooled. The sealing effectiveness of such joints, dueto inelasticity of the lead components, is insufflcient in most cases;moreover, the lead joints cannot be re-used after disassembly of thelamp; they fuse already at a temperature of 327C so that they are hardlyapplicable to discharge lamps with a power input of more than 10 kW.

Another lamp is disclosed in US. Pat. No. 3,405,314. The high pressure,high power electric discharge lamp of this US. Pat. No. 3,405,314 cannotbe readily disassembled because of the extensive length of the packingcollar which is made of a suitable material interposed between arc tubeand electrode assembly.

U.S. Pat. No. 3,543,070 discloses a high pressure electric dischargelamp wherein that portion of the base assembly is cooled which faces thedischarge. The circumferential joint on the art tube is exposed tosubstantial radiation from the discharge space. This lamp cannot bereadily disassembled since joining of the base assembly to the arc tubeis effected by means of a sealant which must be softened when effectingdisassembly and assembly.

According to U.S. Pat. No. 3,366,814, the joining between arc tube andbase assembly is protected from radiation from the discharge space by aring of tantalum disposed within the discharge space. With high powerelectric discharge lamps having a power input of more than about 10 kW,however, this type of protection is insufficient for resilient packingrings for use in separable lamps.

It is an object of the present invention to provide a high pressureelectric discharge lamp with separable base assembly in which allcomponents are sufficiently cooled, and to permit use of commerciallyavailable and inexpensive packings or seals having the requiredproperties, such as temperature resistance, resiliency, separability,sealing efficiency, re-usability and long life.

SUBJECT MATTER OF THE PRESENT INVENTION Both the arc tube and theelectrode tube are provided with flanges which are pressed together andsupported by portions of the base assembly; the main portion of the baseassembly facing the electrode is a clamping ring, and the main portionof the base assembly facing outwardly is a coupling flange. Both membershave ducts and are interconnected by tubes associated with the clampingring (hereinafter called clamping ring tubes), and the base assemblyportion facing the electrode carries a cover. The coolant supply tubeprojecting into the electrode is secured in the base assembly, thepacking and intermediate rings located between the base assemblyportions are of resilient material, and the base assembly portions areso designed as to allow cooling liquid to flow through the coolantsupply tube secured in the base assembly to the tip of the electrode,passing then from the electrode tip through ducts in the coupling flangeradially outwardly, then flowing through some clamping ring tubes to theclamping ring, passing through the latter, returning through otherclamping ring tubes to the coupling flange, and reaching through ductsin said flange the outlet tube.

In one embodiment of the base assembly, the coupling flange is providedwith first ducts which establish connections to the clamping ring tubesand to the clamping ring and open into the space between electrode tubeand coolant supply tube, and with second ducts which establish likewiseconnections to the clamping ring tubes and to the clamping ring but openinto an annular outlet passage within the coupling flange. The secondducts are therefore located more closely to the axis than the firstducts. The outlet duct establishing connection to the outlet tube openslikewise into the annular outlet passage. A washer or gasket is affixedto the coupling flange to prevent the coolant from returning from theannular outlet passage into the space between electrode tube and coolantsupply tube during backflow from the clamping ring via the clamping ringtubes and the coupling flange. This washer or gasket seals the annularoutlet passage as well as the ducts opening into this passage from thespace between electrode tube and coolant supply tube. The washer isprovided with bores through which the coolant liquid, coming from theelectrode, can reach the ducts of the coupling flange, the clamping ringtubes, and the clamping ring.

The gas-tight connection between the arc tube provided with flanges atboth ends, and the electrode tube likewise provided with flanges, iseffected by pressing together the clamping ring and a central fixturering with interposition of a packing ring, sealing ring or gasket.Interposed between the clamping ring and the flange of the arc tube aretwo half-rings of metal and two half-rings of resilient material. Theclamping ring has a central bore which must be larger than the diameterof the arc tube flange to permit the ring to he slipped over the flange.

In an embodiment of the base assembly, the clamping ring tubes guidingthe coolant from the coupling flange to the clamping ring and viceversa, are pressed into the clamping ring in fluid-tight manner. Joiningof the clamping ring tubes provided in the coupling flange is effectedby a packing ring or seal, each, and by a metal sleeve. The metal sleevebears against the central fixture ring.

Intense cooling of the clamping ring is effected by flow of coolantthrough a circumferential groove thereof. Joining of saidcircumferential groove is effected by a ring of resilient material whichin turn is supported by the cover of the clamping ring. The cover of theclamping ring protects the base assembly from radiation from thedischarge space.

In an embodiment, the cover of the clamping ring embraces the clampingring. To permit its removal and re-insertion, it is composed of twoparts which are held together by a tubular jacket.

Due to the highly effective cooling of the base assembly, resilientplastic may be used as the material for the resilient structuralcomponents. The plastic must be resistant to temperatures of up to about200 C for extended periods of time because of degassing of the lampprior to filling.

The base assembly is suited for high power discharge lamps having apower input of about kW, e.g., for high pressure xenon electricdischarge lamps.

FIGS. 1-4 are generalized views of the base assembly according to theinvention;

FIG. 1 is a fragmentary longitudinal view of the base assembly;

FIG. 2 is a transverse section through the base assembly along line A-Bof FIG. 1;

FIG. 3 is a fragmentary, longitudinal, angled section along line C-O-Dof FIG. 2; and

FIG. 4 is a fragmentary, longitudinal section along line C-O-E of FIG.2.

Both are tube 1 of quartz glass and electrode tube 2 (FIG. 1) areprovided at their respective ends with flanges which are pressedtogether and supported by portions of the base assembly. The mainportion of the base assembly facing the electrode is clamping ring 4.The main portion facing outwardly is coupling flange 5. Coupling flange5 is provided with ducts or bores 21, 22 (shown in FIGS. 2, 3, 4) whichserve to supply coolant to the clamp ring tubes 10 (FIGS. 2 and 4) andto clamp ring 4, while ducts or bores 21 22 (FIGS. 2 and 3) serve forpassage of the coolant from the clamp ring tubes 10 (FIGS. 2 and 3)through coupling flange 5 and outlet duct 24 to outlet tube 25. Clampring 4 and coupling flange 5 are interconnected by clamp ring tubes 10,10. The gas-tight connection of the flanges of arc tube 1 and ofelectrode tube 2 is effected by insertion and pressing together of aresilient O-ring 8 within said flanges. Pressing together of O-ring 8 iseffected by tightening of screws 9 (FIG. 1) which bear with their headsagainst central fixture ring 3. Embedded in central fixture ring 3 isthe flange of electrode tube 2. Screws 9 draw the cooled clamping ring 4towards the quartz glass flange of arc tube 1 by the interposition ofhalf-rings 6 and 7. The half-rings 6 are inserted in clamping ring 4 andconvey the tightening pressure to the half-rings 7 of resilientmaterial, to the quartz glass flange and the O-ring 8. Coupling flange 5is connected with central fixture ring 3 by screws 14. When tighteningthe screws 14, coupling flange 5 is pressed together with centralfixture ring 3 against the flange of electrode tube 2, in the course ofwhich sealing of the coolant in the electrode tube is effected by theinterposition of an O-ring l5.

Clamping ring 4 has a central bore which must be larger than thediameter of the quartz glass flange of arc tube 1 to permit slipping itover the quartz glass flange. As is to be seen from FIGS. 3 and 4,clamping ring 4 has in addition a duct formed as a circumferentialgroove 11 on the side facing the discharge for passage of coolant, andon the opposite side four concentrically arranged bores into which thefour clamp ring tubes l0, 10 are pressed in fluid-tight manner. Twobores and clamp ring tubes 10 at a time are used for supply of coolantto the clamp ring, and the other two bores and clamp ring tubes 10 areused for return flow of the coolant from clamp ring 4 to coupling flange5.

Metal sleeves 16 and O-rings 17 are slipped over clamp ring tubes 10, 10between central fixture ring 3 and coupling flange 5 to effect seal ofthe path of the coolant.

A two-part cover 12 of the clamp ring on the side of clamp ring 4 facingthe discharge, shields the radiationsensitive portions 7, 8, 13 of thebase assembly from radiation from the discharge space. Its central boreis therefore held as small as possible, i.e., only slightly larger thanthe outer diameter of arc tube 1. The cover 12 of the clamp ringprevents moreover that the O-ring 13 is pushed out of circumferentialgroove 11 of clamp ring 4. Tubular jacket 26 keeps the two parts of thecover 12 of the clamp ring together.

The packing and intermediate rings 7, 8, 13, l5, 17 which are interposedbetween the base-assembly components are made from a materialcommercially available under the trade name Viton." The metal parts ofthe base assembly are made from an aluminum alloy.

Threaded holes (not shown), cut in coupling flange 5, are used to mountthe lamp and to connect the electric leads.

Details and operation of coupling flange 5 and of further structuralcomponents, and path of the coolant:

The coolant is passed through an inlet tube 18 axially secured tocoupling flange 5 and through a coolant supply tube 19 to the electrodetip (not shown) and from there back to the base assembly between coolantsupply tube 19 and electrode tube 2. Here, the coolant passes throughtwo bores of washer 20 to the two concentric ducts 21 in coupling flange5. Washer 20, of metal, and provided with two bores is secured to flange5 and guides the coolant coming from the electrode to enter only ducts21 but not ducts 21 of coupling flange 5 (FIG. 2). The coolant continuesits flow through ducts 22 of coupling flange 5 radially outwardly. ltreaches clamping ring 4 coaxially through the two ring tubes 10, flowsin circumferential groove 11 of the ring and cools ring 4 and theadjacent packing rings 7, 13. The coolant then flows back coaxially tocoupling flange 5 from ring 4 through the two clamp ring tubes 10 (FIG.2) offset by relative to the two clamp ring tubes 10. In coupling flange5 the coolant flows through the two ducts 22 radially inwardly andthrough the two ducts 21 coaxially into annular outlet passage 23. Ducts21, 22' are offset by 90 relative to ducts 21, 22 (FIG. 2). In addition,ducts 21 of coupling flange 5 are located somewhat nearer the centerthan ducts 21 so as to establish connection (FIGS. 2, 3) to annularoutlet passage 23. The liquid leaves the base assembly through an outletpassage 24 in coupling flange 5 and through the outlet tube 25eccentrically secured in coupling flange 5.

Exhaustion and filling of the lamp with the discharge gas may beaccomplished e.g., through a valve provided at the flange of electrode 2(not shown).

Cooling of the clamping ring and shielding of the cover of the clampingring prevents the temperature of the resilient sealing elements fromrising to impermissibly high values so that commercially availablematerials and stock may be used. This permits quick and easy disassemblyof the lamp. The base assembly remains gastight when subjected tosub-atmospheric pressure (during cleaning) as well as when subjected toexcess pressure (during operation) and can readily be degassed at about200 C for an extended period of time prior to filling. Due to theintense cooling of the entire base assembly and of the electrode tube,the extension of the arc tube may be of reduced length. Thermalexpansion of the tightening screws which clamp the lamp components isprevented.

No noticeable impairment of lamp characteristics could be detected evenafter many hundred hours of operation and repeated disassembly, cleaningand reassembly of 20 kW high pressure xenon discharge lamps having thebase assemblies and intensely cooled electrodes according to theinvention.

Various changes and modifications may be made within the scope of theinventive concept.

I claim:

1. Separable electric discharge lamp having a fluidcooled base assemblyand a fluid-cooled electrode assembly, separable from the base assembly,and being essentially a body of rotation having an axis, comprismg aflange (5) formed on the base assembly;

a separable arc tube (1) and electrode tube (2),

forming said electrode assembly, each tube being formed with a flange;

a clamp ring (4) clamping said flanges together in overlapping relation;

duct means (11, 21, 22; 21', 22, 24) formed in said base assembly flange(5) and in the clamp ring (4);

axially extending connecting tubes (10, connecting said duct means;

a cooling fluid supply and return tube means (19) secured to the baseassembly and extending into the lamp to supply cooling fluid to theelectrode to cool the electrode, and return the fluid to the baseassembly, the tube means communicating with, and forming part of a flowpath including first selected ones of the duct means (22) in the baseassembly flange (5) extending laterally from an axial region towards acircumferential region thereof, said first selected ones of the ductmeans (22) communicating with first axially extending connecting tubes(10) and with the duct means (11) formed in the clamping ring (4);

said duct means (11) in the clamping ring (4) communicating with secondaxially extending connecting tubes (10') and laterally extending ones ofthe duct means (22, 21) in the base assembly (5), and fluid outlet means(23, 24, 25) formed in the base assembly communicating with thelaterally extending outlet duct means;

and resilient sealing means (7, 8, l3, l5, l7) sealing the flanges ofthe lamp together.

2. Lamp according to claim 1, further comprising a fluid directing platesecured to the base assembly flange, the fluid directing plate beingformed with openings establishing fluid communication between the returnflow from the electrode and the first selected ones of the duct means.

3. Lamp according to claim 1, comprising a connecting ring (3)connecting the base assembly flange (5) and the clamping ring (4);

and wherein the resilient sealing means comprises a first packing ring(8) located between the arc tube (1) and the electrode tube (2) and heldin sealing relation by said clamping ring (4) and a sealing ring (15)located between the connecting ring (3) and the base assembly flange(5). 4. Lamp according to claim 3, wherein the axially extendingconnecting tubes (l0, 10') are sealed into the clamping ring (4);

a metal sleeve (16) is provided for each connecting tube surrounding therespective tube and joining the respective connecting tube to the baseassembly flange (5), one end of the sleeve bearing against theconnecting ring (3) and the other end thereof bearing against the baseassembly flange (5);

and sealing means to seal said tubes to the ducts in the base assemblyflange (5).

5. Lamp according to claim 1, further comprising two superposedsectional rings (6, 7) located between the flange of the arc tube (1)and the clamping ring (4), one of said sectional rings (6) being ofmetal and the other of said sectional rings (7) being of resilientmaterial.

6. Lamp according to claim 1, further comprising cover means (12)secured to the base assembly, the resilient sealing means (13) sealingthe cover means to the duct means (11) in the clamp ring (4).

7. Lamp according to claim 6, wherein the clamp ring (4) is formed witha circumferential groove to provide said duct means therein, theresilient sealing means (13) comprising a sealing ring located beneaththe cover means (12) and sealing said groove (11) against the covermeans.

8. Lamp according to claim 6, wherein the cover means is a two-partcover.

9. Lamp according to claim 8, further comprising a tubular jacket (26)securing the parts of the cover means together.

10. Lamp according to claim 1, wherein at least some of the resilientmeans comprises a resilient plastic material having a continuoustemperature tolerance of up to about 200 C.

11. Lamp according to claim ll, wherein the lamp is a discharge lamp ofpower input of between 10 kW to 30 kW.

12. Lamp according to claim 1, wherein the lamp is a high pressure xenondischarge lamp.

l3. Lamp according to claim 1, wherein the cooling fluid is a liquid andthe ducts are dimensioned for liquid flow.

l4. Lamp according to claim 1, wherein the axially extending connectingtubes (10, 10') are sealed into the clamping ring (4);

the clamping ring being formed with a circumferential groove (lll) toprovide said duct means therein, said groove communicating with saidaxially extending connecting tubes to provide fluid flow from a tube(10) through at least a portion of the circumferential groove (11) andout another axially extending tube (10);

and separable sealing means (16, 17) are provided sealing said tubes tothe base assembly flange (5) in position to communicate with saidlaterally extending duct means (2, 22').

' UNITED STATES I PATENT owner CERTIFICATE 9F E CTKN Patent No. 3 ,81 6784 Dated June 1 '1 9 1 974 lnven fl Gerhard WENINGER It is certifiedthat error appears in the ebove-identified patent and that said LettersPatent are hereby corrected as shown below:

I The assignee should read as follows Patent-Treuhand-Gesellschaft furelektrische Gluhlampen mbH M Signed and sealed this 24th day of December1974.

(SEAL) Attest:

:--zcoY M. GIBSOZ? JR. 6. MARSHALL DANN Arresting Officer Commissionerof Patents FORM Po-wso (10-69) USCOMWDC 6037M Y U.S. GOVERNMENT PRINTINGOFFICE: I969 0-366-33 L

1. Separable electric discharge lamp having a fluid-cooled base assemblyand a fluid-cooled electrode assembly, separable from the base assembly,and being essentially a body of rotation having an axis, comprising aflange (5) formed on the base assembly; a separable arc tube (1) andelectrode tube (2), forming said electrode assembly, each tube beingformed with a flange; a clamp ring (4) clamping said flanges together inoverlapping relation; duct means (11, 21, 22; 21'', 22'', 24) formed insaid base assembly flange (5) and in the clamp ring (4); axiallyextending connecting tubes (10, 10'') connecting said duct means; acooling fluid supply and return tube means (19) secured to the baseassembly and extending into the lamp to supply cooling fluid to theelectrode to cool the electrode, and return the fluid to the baseassembly, the tube means communicating with, and forming part of a flowpath including first selected ones of the duct means (22) in the baseassembly flange (5) extending laterally from an axial region towards acircumferential region thereof, said first selected ones of the ductmeans (22) communicating with first axially extending connecting tubes(10) and with the duct means (11) formed in the clamping ring (4); saidduct means (11) in the clamping ring (4) communicating with secondaxially extending connecting tubes (10'') and laterally extending onesof the duct means (22'', 21'') in the base assembly (5), and fluidoutlet means (23, 24, 25) formed in the base assembly communicating withthe laterally extending outlet duct means; and resilient sealing means(7, 8, 13, 15, 17) sealing the flanges of the lamp together.
 2. Lampaccording to claim 1, further comprising a fluid directing plate (20)secured to the base assembly flange, the fluid directing plate beingformed with openings establishing fluid communication between the returnflow from the electrode and the first selected ones of the duct means.3. Lamp according to claim 1, comprising a connecting ring (3)connecting the base assembly flange (5) and the clamping ring (4); andwherein the resilient sealing means comprises a first packing ring (8)located between the arc tube (1) and the electrode tube (2) and held insealing relation by said clamping ring (4) and a sealing ring (15)located between the connecting ring (3) and the base assembly flange(5).
 4. Lamp according to claim 3, wherein the axially extendingconnecting tubes (10, 10'') are sealed into the clamping ring (4); ametal sleeve (16) is provided for each connecting tube surrounding therespective tube and joining the respective connecting tube to the baseassembly flange (5), one end of the sleeve bearing against theconnecting ring (3) and the other end thereof bearing against the baseassembly flange (5); and sealing means to seal said tubes to the ductsin the base assembly flange (5).
 5. Lamp according to claim 1, furthercomprising two superposed sectional rings (6, 7) located between theflange of the arc tube (1) and the clamping ring (4), one of saidsectional rings (6) being of metal and the other of said sectional rings(7) being of resilient material.
 6. Lamp according to claim 1, furthercomprising cover means (12) secured to the base assembly, the resilientsealing means (13) sealing the cover means to the duct means (11) in theclamp ring (4).
 7. Lamp according to claim 6, wherein the clamp ring (4)is formed with a circumferential groove to provide said duct meanstherein, the resilient sealing means (13) comprising a sealing ringlocated beneath the cover means (12) and sealing said groove (11)against the cover means.
 8. Lamp according to claim 6, wherein the covermeans is a two-part cover.
 9. Lamp according to claim 8, furthercomprising a tubular jacket (26) securing the parts of the cover meanstogether.
 10. Lamp according to claim 1, wherein at least some of theresilient means comprises a resilient plastic material having acontinuous temperature tolerance of up to about 200* C.
 11. Lampaccording to claim 1, wherein the lamp is a discharge lamp of powerinput of between 10 kW to 30 kW.
 12. Lamp according to claim 1, whereinthe lamp is a high pressure xenon discharge lamp.
 13. Lamp according toclaim 1, wherein the cooling fluid is a liquid and the ducts aredimensioned for liquid flow.
 14. Lamp according to claim 1, wherein theaxially extending connecting tubes (10, 10'') are sealed into theclamping ring (4); the clamping ring being formed with a circumferentialgroove (11) to provide said duct means tHerein, said groovecommunicating with said axially extending connecting tubes to providefluid flow from a tube (10) through at least a portion of thecircumferential groove (11) and out another axially extending tube(10''); and separable sealing means (16, 17) are provided sealing saidtubes to the base assembly flange (5) in position to communicate withsaid laterally extending duct means (2, 22'').